Method and system for automatic frequency control optimization

Abstract

A method and apparatus for automatic frequency control in a receiver of a wireless device, the method determining a channel estimation for a received signal; calculating a signal to noise ratio for the channel estimation; applying a weighting factor determined based on the calculated signal to noise ratio for the channel estimation to the channel estimation to create a weighted channel estimation; and supplying the weighted channel estimation to a voltage controlled oscillator.

The invention claimed is: 
     
       1. A method for automatic frequency control in a receiver of a wireless device comprising:
 determining a channel estimation for a received signal; 
 applying a weighting factor determined based on a channel quality for the channel estimation to the channel estimation to create a weighted channel estimation; and 
 utilizing the weighted channel estimation for frequency control. 
 
     
     
       2. The method of  claim 1 , wherein the weighting factor is determined based on a predetermined minimum signal to noise ratio. 
     
     
       3. The method of  claim 2 , wherein the weighting factor is zero if the channel quality for the channel estimation is less than the predetermined minimum channel quality. 
     
     
       4. The method of  claim 2 , wherein the weighting factor is further determined based on a predetermined maximum channel quality, the maximum channel quality being a predetermined offset value above the minimum channel quality. 
     
     
       5. The method of  claim 4 , wherein the weighting factor is one if the channel quality for the channel estimation is greater than the maximum channel quality. 
     
     
       6. The method of  claim 4 , wherein the weighting factor is a linearly varied value if the channel quality for the channel estimation is between the predetermined minimum and maximum. 
     
     
       7. The method of  claim 6 , wherein the weighting factor equals the minimum channel quality subtracted from the channel quality of the channel estimation, the value of Which is further divided by the difference between the maximum channel quality and the minimum channel quality. 
     
     
       8. The method  claim 1 , further comprising converting the weighted channel estimation to volts. 
     
     
       9. The method of  claim 8 , wherein the utilizing comprising supplying the voltage from the weighted channel estimation to a voltage controlled oscillator, and further comprising applying an output from the voltage controlled oscillator to a down converter. 
     
     
       10. A frequency correction system in a receiver comprising:
 a down converter having a first input for a received signal and a second input: 
 a channel estimation block, the channel estimation block receiving a signal from the down converter and providing a channel estimation; 
 a weighting function block configured to determine a weighting function based on a channel quality for the channel estimation, the weighting function block providing a weighted channel estimation; 
 a converter block to convert the weighted channel estimation to volts; and 
 a voltage controlled oscillator receiving the converted weighted channel estimation and providing the second input. 
 
     
     
       11. The communications subsystem of  claim 10 , wherein the weighting function is determined based on a predetermined minimum channel quality. 
     
     
       12. The frequency correction system of  claim 11 , wherein the weighting factor is zero if the channel quality for the channel estimation is less than the predetermined minimum channel quality. 
     
     
       13. The frequency correction system of  claim 11 , wherein the weighting factor is further determined based on a maximum channel quality, the maximum channel quality being a predetermined offset value above the minimum channel quality. 
     
     
       14. The frequency correction system of  claim 13 , wherein the weighting factor is one if the channel quality of the channel estimation is greater than the maximum channel quality. 
     
     
       15. The frequency correction system of  claim 13 , wherein the weighting factor is a linearly varied value if the channel quality for the channel estimation is between the predetermined minimum channel quality and the maximum channel quality. 
     
     
       16. The frequency correction system of  claim 15 , wherein the weighting factor equals the minimum channel quality subtracted from the channel quality of the channel estimation, the value of which is further divided by the difference between the maximum channel quality and the minimum channel quality.